What changed

• Adds six actions you can assign to AirPods stem gestures: Stop, Fast Forward, Rewind, Mute Music, Cycle Noise Control, Toggle Transparency.
• Restores noise-control cycling on any gesture slot. Previously, assigning any long-press action stripped the stem's native ANC cycle; the new Cycle Noise Control action brings it back and can be placed on any press type (single / double / triple / long, either side).
• Noise-control actions only appear on models that support them. The long-press warning about overriding ANC cycle hides automatically when long-press is mapped to the new cycle action.

Technical Context

• StemAction migrates from a flat enum to a sealed interface with @Serializable @SerialName(…) data objects, so future parameterized actions can be added without another call-site sweep.
• On-disk profiles reset once on first launch after upgrade (bare-string → discriminated-object wire form). Accepted because the app is currently on testing tracks only.
• StemPressReaction intentionally does NOT inject DeviceMonitor — that would create a Hilt cycle via AapLifecycleManager. Instead it reads live AAP state from AapConnectionManager.allStates with a profile-learned-values fallback (same pattern StemConfigSender already uses).
• The gesture cycle helper strictly honours resolvedAncCycleMask + allowOffOption?.enabled + pendingAncMode, so rapid repeat presses advance from the pending target rather than stale state, and the gesture cycle matches what the Noise Control dialog says.
• ToggleAncTransparency is stateless: leaving Transparency prefers ON, falls back to ADAPTIVE, then OFF.
• MuteToggle targets STREAM_MUSIC explicitly (not the currently-suggested stream) — intent is "mute my music", not "mute whatever Android routes next".
• Capability gating for the dropdown derives from device?.model ?: profile?.model and is split per action: CycleAnc requires hasListeningModeCycle, ToggleAncTransparency requires hasAncControl. An already-configured action always stays visible inside its own dropdown row.

Review checklist

• First launch after upgrade with existing profiles: profile container resets (expected on testing track)
• On AirPods Pro 2 / Pro 3: Cycle Noise Control advances through the cycle configured in the Noise Control dialog, and respects "Allow Off"
• On a model without hasListeningModeCycle: Cycle Noise Control is hidden from the dropdown; Toggle Transparency still appears if the model has ANC
• Long-press info box hides when long-press is mapped to Cycle Noise Control; reappears for other long-press mappings
• Mute Music mutes music playback specifically (not ringer / call audio)